projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| c65fedcf KB |
1 | /*- |
| 2 | * LstOpen.c -- | |
| 3 | * Open a list for sequential access. The sequential functions access the | |
| 4 | * list in a slightly different way. CurPtr points to their idea of the | |
| 5 | * current node in the list and they access the list based on it. | |
| 6 | * If the list is circular, Lst_Next and Lst_Prev will go around | |
| 7 | * the list forever. Lst_IsAtEnd must be used to determine when to stop. | |
| 8 | * | |
| 9 | * Copyright (c) 1988 by University of California Regents | |
| 10 | * | |
| 11 | * Permission to use, copy, modify, and distribute this | |
| 12 | * software and its documentation for any purpose and without | |
| 13 | * fee is hereby granted, provided that the above copyright | |
| 14 | * notice appears in all copies. Neither the University of California nor | |
| 15 | * Adam de Boor makes any representations about the suitability of this | |
| 16 | * software for any purpose. It is provided "as is" without | |
| 17 | * express or implied warranty. | |
| 18 | */ | |
| 19 | #ifndef lint | |
| 20 | static char *rcsid = | |
| 21 | "$Id: lstOpen.c,v 1.6 88/11/17 20:53:43 adam Exp $ SPRITE (Berkeley)"; | |
| 22 | #endif lint | |
| 23 | ||
| 24 | #include "lstInt.h" | |
| 25 | ||
| 26 | /*- | |
| 27 | *----------------------------------------------------------------------- | |
| 28 | * Lst_Open -- | |
| 29 | * Open a list for sequential access. A list can still be searched, | |
| 30 | * etc., without confusing these functions. | |
| 31 | * | |
| 32 | * Results: | |
| 33 | * SUCCESS or FAILURE. | |
| 34 | * | |
| 35 | * Side Effects: | |
| 36 | * isOpen is set TRUE and curPtr is set to NilListNode so the | |
| 37 | * other sequential functions no it was just opened and can choose | |
| 38 | * the first element accessed based on this. | |
| 39 | * | |
| 40 | *----------------------------------------------------------------------- | |
| 41 | */ | |
| 42 | ReturnStatus | |
| 43 | Lst_Open (l) | |
| 44 | register Lst l; | |
| 45 | { | |
| 46 | if (LstValid (l) == FALSE) { | |
| 47 | return (FAILURE); | |
| 48 | } | |
| 49 | ((List) l)->isOpen = TRUE; | |
| 50 | ((List) l)->atEnd = LstIsEmpty (l) ? Head : Unknown; | |
| 51 | ((List) l)->curPtr = NilListNode; | |
| 52 | ||
| 53 | return (SUCCESS); | |
| 54 | } | |
| 55 |